Insulation piercing terminal



y 1961 F. KLUMPP, JR 2,982,938

INSULATION PIERCING TEMINAL Filed March 14, 1956 INVENTOR. FERDINAND KLUMPP, JR.

United States Patent 2,982,938 INSULATION PIERCING TERMINAL Ferdinand Klumpp, Jr., 691 Fairfield Way, Union, NJ. Filed Mar. 14, 1956, Ser. No. 571,445

3 Claims. (Cl. 339-97) My invention relates to conductor terminals of the blade or female type and useful in connection with connectors such as plugs for electrical cords or as terminal members for flexible cords, and to their method of manufacture. My invention is an improved type of terminal particularly suitable for use with conducting electrical cords of the tinsel variety, although not limited thereto.

Conducting cords of the tinsel variety consist of very fine flexible conductors interwoven with thread to provide a larger diameter conducting element and having an insulating coating or cover. This type of conductor is very difficult to strip bare since in the stripping operation invariably fine conductors are torn or cut, reducing the number of conductors in the cord and resulting in frayed ends which are diflicult to handle when attaching to a terminal member. ing almost always results in the destruction of many of the fine wires due to the heat of soldering. As a result, solderless terminals are normally used.

In the formation of the blanks which are later formed into blade terminals or tip terminals having a conductor receiving sleeve at one end, the flat stock is punched with a die having a triangularly, shaped cross-section to provide a prong. The prong is usually of a triangular shape and extends at an angle to the blank with its base attached to the blank and is provided at its free end with a sharp, piercing point. These prongs are of small dimensions and must be strong enough and sharp enough to pierce the insulation and embed themselves deeply into the woven mesh conductors to make good contact therewith as the sleeve is formed around the engaged conductor in the area of the prong. With this arrangement it is unnecessary to strip or solder the wire, since it is firmly engaged by the prong or prongs and the sleeve which is formed and tightly wrapped around the insulated conductor.

The prongs must be sharp if the terminal is to pierce instead of tear the insulation and if the prongs are to embed themselves into the woven or stranded conductor mass with good electrical contact. Additionally, since the conductor engaging sleeves of the terminals are small in area, the prongs should be formed from the blanks in such fashion as to provide enough metal for the prongs without weakening the remaining portion of the blanks from which the sleeve is formed. Furthermore, the shape of the punched blank before being formed into an engaging sleeve should be such that the terminals can be punched from a continuous strip of fiat stock with a minimum of wastage of metal stock.

I have also found that with the conventional die used for piercing and forming the, pointed prongs, the die and punches soon become dull at the pointed, end due to its small transverse dimension and the tremendous forces exertedby it in punching operations. This, in turn, results in poorly formed and dull prongs which is highly objectionable. The punches and dies frequently break.

In accordance with my invention, I provide a conductor terminal punched or formed from fiat stock which terminates" at one end with a sleeve portion having a plurality of generally triangularly-shaped cord engaging fingers and one or more generally triangularly-shaped prongs spaced from each other on opposite sides of an elongated aperture. As will be explained in greater de- In addition to this difficulty, solder 2,982,938 Patented May 2, 1961 "ice insure deep penetration of the conductor and maximum contact therewith. Furthermore, by first punching an elongated aperture followed by a severing and bending, operation, I insure a well formed and sharp prong and increase the life of the punching, severing and forming,

dies.

It is therefore an object of my invention to provide an improved form of conductor terminal which may be used for any type of wire but which is particularly suitable for use with tinsel wire and which requires no stripping of the conductor and no soldering.

It is another object of my invention to provide such a terminal member which is provided with piercing prongs of novel construction and so related to the sleeve member as to minimize weakening of the sleeve portion of the terminal member and to insure a strong, tight engagement with an insulated conductor.

A still further object of my invention is to provide a novel construction of the piercing prongs of a terminal connector and a novel method of making the prongs .so as to insure a sharp, piercing prong.

Still another object of my invention is to provide a novel method of forming sharp, piercing prongs on a terminal connector while, at the same time, increasing the life of the die and forming punches for shearing the metal blanks and forming the prongs.

Other objects of the invention will appear in thefollowing description with reference to the drawings, in which:

Fig. l is a side elevation of a plug partially in section utilizing a formed terminal blade and made according to my invention;

Fig. 2 is a perspective of my invention applied to a female type terminal connection;

Fig. 3 is a plan view of a blade terminal made according to my invention and formed to shape prior to attaching to an insulated conductor;

Fig. 4 is a side elevation of Fig. 3;.

Figs. 5 and 6 are terminal connector blanks illustrating two of the steps in forming the piercing prongs made according to my invention;

Fig. 7 is a right-end view of Figs. 3 and 4; and

Fig. 8 shows details of a piercing tool and a step in the making of a terminal connector in accordance with my invention.

Referring to Fig. l, the plug 10 has received within it apair of blade terminals 11 and 12 of the spring type attached to insulated cords 13 and 14 and made according to my invention. In Fig. 21 show a tip type female terminal member 15 which also employs my invention and attached to a cord 16.

, As shown in Figs. 3, 4, and 5, the terminal member, in this case a blade type terminal made from flat stock, has one elongated portion 20 having at its free end the trough-like portion 21 which provides the conductor engaging sleeve provided with the pointed tangs or fingers 22, 23 and 24 which engage theinsulating coating of the conductor and are partially embedded therein as best shown in Fig. 2. The piercing prongs 26 and 27 are formed from the sleeve and positioned centrally thereof and extend inwardly of the sleeve portion. As shown, they lie in a common plane but need not necessarily.

The other folded-over portion 30 may be provided with a tang or lug 31 which is formed to extend normally of the folded-over portion. This not only serves as an abutment member for the insulated conductor 13, 14, or 16 but also serves to secure the blade within the plug 10.

The novel method of forming a plurality of prongs 3 simultaneously in a blank while at the same time insuring sharp, piercing points and also prolonging punch or die life is illustrated in Figs. 5 and 6.

Referring to Fig. 5, a blank is first punched from fiat stock. The method of punching and forming may be that illustrated in my Patent 2,558,052 except for the formation of the prongs 26 and 27. When the blanks are cut to shape as illustrated in Fig. 5, I first punch out the rectangular-shaped aperture 35. This can be done with a die having a transverse section the shape of the aperture 35. There are no sharpened portions or points on this punch 'or die which can be quickly dulled or broken. This piercing operation is followed by a second piercing operation using a punch and die of more or less triangular cross section which then severs the blank along the lines 26 and 27 to make the teeth 26 and 27.

As best shown in Fig. 8, after the first step of punching out the aperture, such as 35 in Fig. 5 or 35' in Fig. 7, I use a punch and forming tool 40 having a generally triangular shape to cut along the lines 26' and 27 or 26 and 27". The relationship of the piercing and forming tool is shown in Fig. 8. It will be seen that the point 40' does not engage any metal in being within the aperture, and hence it can never be dulled or broken. This was not previously the case. As the punch 40 continues through the blank, it folds or bends the resulting prongs 26 and 27 into a position normal to the blank, thus providing a pair of prongs adjacent each other. The cuts 26' and 27 extend substantially to the bottom boundary 35' of the aperture 35. It is obvious that the punch need not necessarily be trianguler, so long as it is shaped to sever the blank along the lines 26, 27 and 26", 27".

Since the diagonal sides of the prongs or teeth taper away from each other when forced into the insulation and tinsel wires, they tend to force the wires or fine strands away from each other in a combing manner to open the strands longitudinally of the conductor and insure a good, tight contact, the strands being pressed against the sides of the prongs as the fingers or teeth 22, 23 and 24 are wrapped around the wire. Thus, penetration of the conductor strands plus good contact with the prongs 26 and 27 over a large area is insured. At the same time there is no problem of replacing dies and punches frequently because of dull points on the punches. Sharp prongs are thus always assured.

Another advantage of a terminal made according to my invention is that since it is not necessary to provide a portion to which the bare conductor is soldered, the overall length of the terminal can be made shorter, thus saving metal stock.

It will be noted that the punched-out metal and the prongs are formed from the blank at that portion of the blank where the area of the metal is a maximum within the sleeve area, that is, in the center and with the points of the prongs extending just within the boundaries of the formed tooth 24. This not only provides the prongs but insures the optimum strength for the engaging finger 24. This permits the formation of a prong having a useable length to pass through the insulation and extend into the conductor cord proper while, at the same time, providing the maximum metal to provide a good, strong finger 24. Recesses 36 and 37 are provided to permit the portion of the blank from the recess to the end of the blank to be formed into a sleeve.

In the form of terminal shown in Fig. 6, I utilize a punched aperture 35' of slightly distorted rectangular shape to provide more or less elongated triangular-shaped prongs 26 and 27".

The method which I have devised for forming prongs not only permits the simultaneous punching of a plurality of prongs of proper shape, but also eliminates rapid dulling of the punch as well as breaking off of the pointed portion, but my method of forming prongs also lends itself to punching heavy stock which in the past took a particularly heavy toll of dies and punches.

While certain specific embodiments have been illustrated and described, it will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

I claim:

1. An elongated conductor terminal to be attached to an insulated conductor and formed from fiat stock and including an elongated member terminating in a sleeve portion, said sleeve portion having an elongated aperture therein with oppositely disposed straight sides extending transversely of the longitudinal axis of said sleeve portion, each of said straight sides having a slit extending transversely from said straight line into said sleeve portion forming an acute portion on one side of the slit, said acute portion being bent up and forming generally triangularly-shaped prongs extending normally to said sleeve portion and spaced from each other on the oppositely disposed sides of said aperture and lying in a plane extending longitudinally of said sleeve portion, said aperture having a substantially transverse dimension to insure the formation of said prongs with a sharp point, the base of said prongs being positioned at one end of said aperture, the opposite longitudinal edges of said sleeve portion comprising a plurality of oppositely disposed teeth, said prongs being adapted to pierce the insulation and contact the conductor of said insulated conductor, and said teeth being adapted to be formed around the insulated coating of said conductor to engage and retain said conductor on said terminal.

2. An elongated conductor terminal to be attached to an insulated conductor and formed from flat stock and including a first elongated member terminating in a sleeve portion, said sleeve portion having an aperture therein with oppositely disposed straight sides extending transversely of the longitudinal axis of said sleeve portion, each of said straight sides having a slit extending transversely from said straight line into said sleeve portion forming an acute portion on one side of the slit, said acute portion being bent up and forming generally triangularly-shaped prongs extending normally to said sleeve portion and spaced from each other on the oppositely disposed sides of said aperture and lying in a plane extending longitudinally of said sleeve portion, said aperture having a substantially transverse dimension to insure the formation of said prongs with a sharp point, the base of said prongs being positioned at one end of said aperture, the opposite longitudinal edges of said sleeve portion comprising a plurality of oppositely disposed teeth, said prongs being adapted to pierce the insulation and contact the conductor of said insulated conductor, and said teeth being adapted to be formed around the insulated coating of said conductor to engage and retain said conductor on said terminal, said terminal including a second elongated member oppositely disposed to said first elongated member and in contact therewith, and provided with a lug adjacent said sleeve portion providing a stop for the end of a conductor engaged by said terminal.

3. The elongated conductor terminal of claim 1, wherein said elongated aperature is trapezoidal in shape.

References Cited in the file of this patent UNITED STATES PATENTS 2,035,947 Davis Mar. 31, 1936 2,302,767 Hackbarth Nov. 24, 1942 2,476,738 Klumpp July 19, 1949 2,501,870 Malhiot Mar. 28, 1950 2,593,743 Galvao Apr. 22, 1952 2,610,390 Locke Sept. 16, 1952 2,618,680 Cook Nov. 18, 1952 2,643,446 Matthysse June 30, 1953 2,727,299 Klumpp Dec. 20, 1955 2,742,549 Peters Apr. 17, 1956 2,820,843 Dreher Jan. 21, 1958 

